The controlling opinion, written by Chief Justice John Roberts, upheld the mandate as a tax, although concluded it was not valid as an exercise of Congress' commerce clause power. Justices Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan joined in the outcome.

There was huge reaction on Twitter to the ruling, from across the online health community. Check out the slideshow to see what they think of the high court decision: